This invention relates to accessing body fluids for diagnostic and therapeutic purposes, and in particular, to a catheter for venous vascular access. More specifically, this invention relates to a reinforced dual lumen catheter for hemodialysis or apheresis procedures requiring bidirectional blood flow.
Extracorporeal treatment of blood requires that the vascular system of a subject be directly accessed, and that the blood be removed and then returned to the subject after removal of various components or toxins, or after addition of oxygen. Extracorporeal treatments include apheresis, or the collection of blood cells, the removal of a specific blood cell type from the blood, or plasma exchange, and hemodialysis, or the removal of various chemical substances from the blood including ingested or injected drugs, or toxins created during normal body metabolism, the presence of which is most often due to renal impairment.
Traditionally, such extracorporeal treatments involves the tapping of the vascular system via a first needle attached to a first catheter. The blood is then circulated through a treatment device, and then returned to the vascular system via a second catheter and needle. This technique requires that the needles be spaced a sufficient distance apart so that treated blood will not reenter the output needle for additional treatment. Adequate needle spacing is also required to prevent collapse of the accessed vein. The problem of vascular collapse becomes compounded if the treatment is one which must be repeated and the vein or fistula becomes weakened with repeated punctures.
Another method of performing extracorporeal blood treatment includes the use of a single needle and catheter accommodating bidirectional flow through which the blood is removed and returned. See, for example, the simple double lumen cather disclosed by Mahurkar in U.S. Pat. No. 4,808,155; a double lumen needle and cannula also disclosed by Mahurkar in U.S. Pat. No. 4,134,402; a dual channeled hypodermic needle disclosed by Grumarud in U.S. Pat. No. 4,203,436; and a hemodialysis catheter with two circular lumens arranged side by side disclosed by Uthmann in U.S. Pat. No. 4,385,631. This method minimizes insertion trauma and reduces potential for clotting. However, this method may not be of use to all patients as flow rates within the needle are limited. In addition, prerequisite to this technique is an intermittent occlusion machine capable of cyclical operation.
A common problem encountered in the extracorporeal treatment of blood is collapse of the catheter due to decreased pressure within the catheter, and subsequent weakening of the catheter walls. Single lumen catheters and tubes have long been reinforced to reduced collapse. See, for example, U.S. Pat. No. 419,926 granted to Chapman in 1890, and U.S. Pat. No. 2,211,975 granted to Hendrickson in 1937; and more recently U.S. Pat. Nos. 4,832,681, 4,737,153, and 4,639,252.
Hence there is a long felt need for a vascular access catheter which will not collapse, which accommodates dual flow therethrough with a sufficient flow rate, and the use of which causes minimal clotting and recycling of treated blood.
Accordingly, it is an object of the present invention to provide an improved catheter allowing for plural flow therein.
It is another object of the invention to provide a reinforced multiple lumen catheter which will not collapse.
Yet another object of the invention is to provide a method of fabricating a reinforced, multiple lumen catheter.